Sidequest for more texture sets in S2

I wanted to try out if it is possible to add a fourth texture set into the original The Settlers II. So I went ahead and copied a few files like MAP_0_Y.LST as MAP_3_Y.LST or GOU5.DAT as GOU8.DAT, as well as modified a map to point to texture 4 and introduced my own customized Greenland texture as TEX8.LST… and what do you know, it works!

The only problem with this, as can be seen from the image, are the texture borders. I don’t know where the game captures this information from. It can’t be from the files I duplicated, because otherwise the information would be correct. It has to come from somewhere else. Figuring out this mystery will be a hard one. In worst case it is some data within the S2.EXE which is quite well beyond my usual modding experience. And I’d like to keep things easy anyway!